paradigms how can the usability of an interactive system be - - PDF document

1 chapter 4

paradigms

why study paradigms

Concerns

– how can an interactive system be developed to ensure its usability? – how can the usability of an interactive system be demonstrated or measured?

History of interactive system design provides paradigms for usable designs

What are Paradigms

• Predominant theoretical frameworks or

scientific world views

– e.g., Aristotelian, Newtonian, Einsteinian ( relativistic) paradigm s in physics

• Understanding HCI history is largely about

understanding a series of paradigm shifts

– Not all listed here are necessarily “ paradigm ” shifts, but are at least candidates – History will judge which are true shifts

Paradigms of interaction

New computing technologies arrive, creating a new perception of the human—computer relationship. We can trace some of these shifts in the history of interactive technologies.

The initial paradigm

• Batch processing

Impersonal computing

Example Paradigm Shifts

• Batch processing
• Time-sharing

Interactive computing

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Example Paradigm Shifts

• Batch processing
• Timesharing
• Networking

??? @#$% !

Community computing

Example Paradigm Shifts

• Batch processing
• Timesharing
• Networking
• Graphical displays

% foo.bar ABORT dumby!!!

C…P… filename dot star… or was it R…M? Move this file here, and copy this to there.

Direct manipulation

Example Paradigm Shifts

• Batch processing
• Timesharing
• Networking
• Graphical display
• Microprocessor

Personal computing

Example Paradigm Shifts

• Batch processing
• Timesharing
• Networking
• Graphical display
• Microprocessor
• WWW

Global information

Example Paradigm Shifts

• A sym biosis of physical

and electronic worlds in service of everyday activities.

• Batch processing
• Timesharing
• Networking
• Graphical display
• Microprocessor
• WWW
• Ubiquitous

Computing

Time-sharing

• 1940s and 1950s – explosive technological

growth

• 1960s – need to channel the power
• J.C.R. Licklider at ARPA
• single com puter supporting m ultiple users

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Video Display Units

• m ore suitable medium than paper
• 1962 – Sutherland's Sketchpad
• computers for visualizing and manipulating

data

• one person's contribution could drastically

change the history of com puting

Programming toolkits

• Engelbart at Stanford Research Institute
• 1963 – augmenting man's intellect
• 1968 NLS/ Augment system demonstration
• the right programming toolkit provides

building blocks to producing complex interactive system s

Personal computing

• 1970s – Papert's LOGO language for simple

graphics programming by children

• A system is m ore powerful as it becom es

easier to user

• Future of computing in small, powerful

machines dedicated to the individual

• Kay at Xerox PARC – the Dynabook as the

ultim ate personal com puter

Window systems and the WIMP interface

• humans can pursue more than one task at a

tim e

• windows used for dialogue partitioning, to

“change the topic”

• 1981 – Xerox Star first commercial windowing

system

• windows, icons, menus and pointers now

fam iliar interaction m echanism s

Metaphor

• relating computing to other real-world activity

is effective teaching technique

– LOGO's turtle dragging its tail – file m anagem ent on an office desktop – word processing as typing – financial analysis on spreadsheets – virtual reality – user inside the m etaphor

• Problem s

– som e tasks do not fit into a given m etaphor – cultural bias

Direct manipulation

• 1982 – Shneiderman describes appeal of

graphically-based interaction

– visibility of objects – increm ental action and rapid feedback – reversibility encourages exploration – syntactic correctness of all actions – replace language with action

• 1984 – Apple Macintosh
• the model-world metaphor
• What You See Is What You Get (WYSIWYG)

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Language versus Action

• actions do not always speak louder than

words!

• DM – interface replaces underlying

system

• language paradigm
• interface as mediator
• interface acts as intelligent agent
• programming by example is both action

and language

Hypertext

• 1945 – Vannevar Bush and the memex
• key to success in managing explosion of

inform ation

• m id 1960s – Nelson describes hypertext as

non-linear browsing structure

• hypermedia and multimedia
• Nelson's Xanadu project still a dream today

Multimodality

• a mode is a human communication

channel

• emphasis on simultaneous use of

multiple channels for input and output

Computer Supported Cooperative Work (CSCW)

• CSCW removes bias of single user /

single computer system

• Can no longer neglect the social aspects
• Electronic mail is most prominent

success

The World Wide Web

• Hypertext, as originally realized, was a

closed system

• Simple, universal protocols (e.g. HTTP)

and mark-up languages (e.g. HTML) made publishing and accessing easy

• Critical mass of users lead to a

complete transformation of our information economy.

Agent-based Interfaces

• Original interfaces

– Com m ands given to com puter – Language-based

• Direct Manipulation/ WIMP

– Com m ands perform ed on “ world” representation – Action based

• Agents - return to language by instilling

proactivity and “intelligence” in com m and processor

– Avatars, natural language processing

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Ubiquitous Computing

“The most profound technologies are those that disappear.” Mark Weiser, 1991 Late 1980’s: computer was very apparent How to make it disappear?

– Shrink and em bed/ distribute it in the physical world – Design interactions that don’t dem and our intention

Sensor-based and Context- aware Interaction

• Humans are good at recognizing the

“context” of a situation and reacting appropriately

• Automatically sensing physical

phenomena (e.g., light, temp, location, identity) becoming easier

• How can we go from sensed physical

measures to interactions that behave as if made “aware” of the surroundings?